IceCube bounds on sterile neutrinos above 10 eV

TL;DR

This paper assesses IceCube's ability to detect sterile neutrinos with masses above 10 eV, finding some evidence for mixing and setting new constraints that surpass previous experiments in certain parameter regions.

Contribution

It demonstrates IceCube's sensitivity to sterile neutrino mixing above 10 eV, including tau neutrino mixing via matter effects, and provides updated bounds and future prospects.

Findings

1. 1-year IceCube data shows a mild preference for sterile neutrino mixing.

2. New upper bounds improve upon Super-Kamiokande and DeepCore constraints.

3. Future data could confirm or further constrain sterile neutrino parameters.

Abstract

We study the capabilities of IceCube to search for sterile neutrinos with masses above 10 eV by analyzing its $\nu_\mu$ disappearance atmospheric neutrino sample. We find that IceCube is not only sensitive to the mixing of sterile neutrinos to muon neutrinos, but also to the more elusive mixing with tau neutrinos through matter effects. The currently released 1-year data shows a mild (around 2$\sigma$) preference for non-zero sterile mixing, which overlaps with the favoured region for the sterile neutrino interpretation of the ANITA upward shower. Although the null results from CHORUS and NOMAD on $\nu_\mu$ to $\nu_\tau$ oscillations in vacuum disfavour the hint from the IceCube 1-year data, the relevant oscillation channel and underlying physics are different. At the $99\%$ C.L. an upper bound is obtained instead that improves over the present Super-Kamiokande and DeepCore constraints in some parts of the parameter space. We also investigate the physics reach of the roughly 8 years of data that is already on tape as well as a forecast of 20 years data to probe the present hint or improve upon current constraints.